This revised R01 grant addresses the problem of relapse of B-lineage acute lymphoblastic leukemia (B-ALL) after allogeneic hematopoietic stem-cell transplantation (HSCT). We hypothesize that the incidence of cancer relapse following allogeneic HSCT can be reduced by targeting post-transplant B-ALL minimal residual disease (MRD) with adoptively transferred donor-derived T cells genetically modified to be specific for CD19. To consolidate HSCT, we have designed a next-generation chimeric antigen receptor (CAR), designated CD19RCD28, to redirect specificity of T cells to the B-cell lineage-restricted cell-surface molecule CD19 independent of major histocompatibility complex (MHC). Genetically modified CD19RCD28+ T cells activated through chimeric CD28 and CD3-6 lyse B-ALL, upregulate production of IL-2 and anti-apoptotic genes, in a CAR-regulated manner. The Sleeping Beauty (SB) system has been combined with electroporation to introduce the CAR as well as co-express HSV-1 thymidine kinase (TK) for imaging by positron emission tomography (PET). The studies in Aim #1 will now evaluate whether an all-human CD19-specific CAR can be developed (hCD19RCD28) that provides a fully-competent activation signal as determined by CD19-dependent killing, cytokine production, and sustained proliferation in T cells that have been genetically modified by SB transposition. A xenogeneic mouse model of disseminated B-lineage tumor will be used to ascertain the feasibility and safety of adoptive therapy using non-invasive bioluminescent imaging (BLI) and <PET to longitudinally asses the persistence of the infused CAR+TK+ cells and the anti-tumor effect. Aim #2 will evaluate the safety, feasibility and persistence, of infusing escalating doses of donor-derived hCD19RCD28+ T cells with/without TK expression, after allogeneic HSCT for high-risk CD19+ B-ALL. T cells expressing TK will be imaged by PET. If necessary, ganciclovir (GCV) will be given for conditional ablation of TK+ cells in the event of serious toxicity. Correlative studies in Aim #3 will delineate the magnitude and persistence of transferred T cells at the prescribed T-cell Dose Levels using vector-specific Q-PCR and TCR spectratyping analyses on serially acquired specimens. Other correlative studies will evaluate the trafficking to sampled bone marrow (BM) of adoptively transferred T cells and the functional status of transferred T cells in this anatomic site of MRD. Human PET imaging using 2'-Deoxy-20-[18F]fluoro-5-ethyl-1-2-D-arabinofuranosyluracil ([18F]-FEAU) metabolized/trapped by TK co-expressed in infused CAR+ T cells, will be used to evaluate the distribution of adoptively transferred T cells. In aggregate, the results of the studies will facilitate the evolution of targeting post-HSCT MRD with donor-derived CD19-specific T cells for enhanced disease-free survival of patients with B-ALL. LAY SUMMARY: We will infuse CD19-specific T cells after transplantation to improve survival for patients with acute lymphoblastic leukemia. PUBLIC HEALTH RELEVANCE: Recurrence of acute lymphoblastic leukemia (ALL) after allogeneic hematopoietic stem-cell transplantation (HSCT) is almost always fatal due to the resistant of the relapsed tumor to conventional therapy. New biologic therapies are urgently needed and one promising approach is to genetically modify T cells to have an improved anti-tumor effect. In this grant application, donor-derived T cells will, for the first time, be engineered to be specific for CD19 molecules on ALL blasts and infused after allogeneic HSCT to reduce the probability of relapse.